Control system



July 10, 1923. 1,461,512 5. M. BQUTQNW 7 CONTROL SYSTEM Filed Sept. 17.1920 46 so L /aa 5a 1 az m a/ 495053 52 f nrwara fie verse 74 ReverseForward a4 7 .92 a 2 l 30 i a0 7 /02 a ,m/

WITNESSES: INVENTOR 427% Edgar M Baum/z .7 M M BY ATTORNEY Patented July10, 1923.

UNITED STATES PATENT OFFICE.

EDGAR H. BOUTON, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- vnnm.

CONTROL SYSTEM.

Application filed September 17, 1920. Serial No. 410,906.

To all whom it may concern:

Be it known that I, EDGAR M. BoUToN, a citizen of the United States, anda resident of Wilkinsburg in the county of Allegheny and State of lennsylvania, bar e. invented a new and useful Improvement in ControlSystems, .of which the following is a specification.

My invention relates to motor-control systems and it has particularrelation to systems for accelerating motors by means of contactors whichare closed in accordance with the counter electromotive force of themotors.

One object of my invention is to provide means for automaticallyshunting the starting resistor of a motor and to provide means forpreventing the shunting of the resistor during electrical braking.

A second object of my invention is to provide means for preventing thestarting of a motor through the auxiliary contacts which close a linecircuit-breaker therefor.

Heretofore the starting resistor in series with the motor has beenautomatically shunted by contactors controlled by thecounter-electromotive force generated by the motor.. The'disadvantage ofthis method, when'the motor is plugged or suddenly reversed to effectelectrical braking, is that the starting resistor is prematurely shuntedby the closure of the contactors that are controlled by the counterelectromotive force, thereby causing excessive current to traverse thearmature circuit of the motor.

Briefly speaking, my invention consists in providing a contactor havingan actuating coil for shunting the. starting resistor, the actuatingcoil being connected in shunt re lation across the armature and one-halfof the starting resistor, and secondly, in pro-. viding resistance inseries with both the start and the stop buttons, which control the linecircuit-breaker for the motor, thereby diminishing the current passingtherethrough and preventing a. heavy rush of current through thearmature.

For a better understanding of my inven tion, reference should now bemade to the accompanying drawings, 7

Fig. 1 of which is a diagrammatic view of a motor-control system.embodying my invention;

Fig. 2 is a schematic diagram of the motor-control system shown in Figs.1 and 3;

field-magnet winding 2 of, the motor 1.

Fig. 3 is a diagrammatic view of a control system similar to that shownin Fig. 1.

Referring particularly to Figs. 1 and 2, a motor 1' having a shuntfield-magnet windmg 2, a series field-magnet winding 3 and an armature4, is energized from supply conductors 5 and 6, through a knife switch7. A master controller 8 is provided for reversmg the current throughthe armature 1 of the motor 1. A field rheostat 9 is provided forcontrolling the strength of the shunt A starting resistor 10, which isconnected in series relation with the motor armature 4,

may beshunted by the closing of a contactor 11.

A three-pole contactor or circuit-breaker 12, having an actuating'coil13, is governed by a start push-button switch 14 and a stop push-buttonswitch 15. A resistor 16 is connected in series relation with the startpush-button switch 14 and a resistor 17 is connected in series relationwith the stop push-button switch 15.

The operation of the s stem is begun by closing the knife switch i andpushing the start push-button 14. These actions establish a circuit fromsupply conductor 18 through resistor 16, contact member 20 of startpush-button 14:, conductor 21, actuating coil 13 of circuit-breaker 12,and conductor 23 to knife switch 7. The completion of this circuitenergize the actuating coil 13 sufficiently to close the circuit-breaker12.

When the circuit-breaker 12 is closed, a holding circuit therefor isestablished from the knife switch 7 through conductor 18, contactmembers 24 and 26 of circuit-breaker 12, resistor 17, contact member 28of stop push-button 15 in its normal closed position, conductor 21,actuating coil 13. of the circuit-breaker 12 and conductor 23 to knifeswitch 7. a

The circuit-breaker 12 being closed, the master controller 8 may be soactuated as to operate the motor in either the forward or the reversedirection. By moving the controller from its off position to its forwardposition, the motor is operated in the forward direction, by a circuitwhich is established from the knife switch 7, through conductor 18,contact member 24 of the circuitbreaker 12, conductor 29, seriesfield-magnet winding 3, conductor 30, contact terminals 31 and 33, whichare bridged by contact I segment 32 of the master controller 8,conductor 34, armature 4 of the motor 1, conductor 35, contact terminal36, contact segment 37, contact terminal 38, conductors 39 and 40,starting resistor 10 and conductors 41 and 23 to the knife switch 7.

Concurrently with the energization of the series field-magnet winding 3,the shunt field-magnet winding 2 is energized by a circuit that extendsfrom knife switch 7 through conductor 18, contact member'24 of thecircuit-breaker 12, conductor 25, shunt field-magnet winding 2 of themotor 1, conductor 44, field rheostat 9 and conductors 45 and 23 to theknifeswitch 7. The armature 4, the shunt field-magnet winding 2 and theseries field-magnet winding 3 of the motor 1 are now energized.

When the start button 14 is pushed, besides establishing a circuitthrough the actuating coil 13 of the circuit-breaker 12, a secondcircuit is established, if the master switch 8 is in its forwardposition, from knife switch 7 through resistor 16, contactmember 20 ofstart button 14, contact member 28 of stop button 15, resistor 17,contact member 26 of circuit-breaker 12, conductors 25 and 29, seriesfield-magnet winding 3, conductor '30, contact terminal 31, contactsegment 32, contact terminal 33, conductor 34, armature 4 of motor 1,conductor 35, contact terminal 36, contact segment 37, contact terminal38, conductors 39 and 40, resistor 10, conductors 41 and 23 to knifeswitch 7. If the resistors 16 and 17 were not in series with the startpushbutton switch 14, a heavy rush of current would take place throughthe push-button, as it is connected through the armature 4 of the motor1 across the supply conductors 5 and 6.

The starting resistor 10 is shunted by the contactor 11, which isoperated by an actuat'ing coil 46. The actuating coil 46 is connectedacross the series field winding 3, the armature4 and approximately halfof the starting resistor 10 when the master controller 8 is in eitherits forward or its reverse position.

When the master controller 8 is in its forward pos tion, a circuit isestablished from knife switch 7 through conductor 18, contact member 24of circuit-breaker 12, conductor 25, contact member 47 of circuitbreaker12, conductor 48, contact terminal 49 of the master controller 8,contact segments 50 and 51, which are electrically con nected, contactterminal 52, conductor 53,

actuating coil 46 of the contactor 11, conductor'54, a portion ofstarting resistor 10 and conductors 41 and 23 to knife switch 7.

The actuating coil 46 is set to close the contactor 11 when energized ata higher current value than if it were connected only across thearmature 40f the motor 1. When the counter electromotive force of themotor 1 energizes the actuating coil 46 of the contactor 11sufficiently, corresponding to suitable accelerating conditions, thecontactor 11 will close, thereby shunting the starting resistor 10 tocomplete the acceleration of the motor.

WVhenever the controller 8 is moved to the reverse position, a circuitis thereby established for the series field-magnet winding 3 and thearmature 4. This circuit extends from knife switch 7 through conductor18, contact member 24 of circuit-breaker 12, conductor 29,. seriesfield-magnet windings 3 of the motor 1, conductor 30, contact terminal31 of the controller 8, segments 58 and 59 which are electricallyconnected, contact terminal 36, conductor 35, armature .4 of the motor1, conductor 34, contact terminal 33 of the controller 8, contactsegments 60 and 61, which are electrically connected, contact terminal38, conductors 39 and 40, starting resistor 10 and conductors 41 and 23to the knife switch 7.

The completion of this circuit causes the rotation of the armature 4 ofthe motor 1 in the opposite direction, as both the shunt field-magnetwinding 2 and the series fieldmagnet winding 3 are energized in the samedirection as they were during the forward operation of the motor 1 andonly the directiOIl of the current through the armature has beenreversed.

Another circuit is established at this time for the actuating coil 46 ofthe contactor 11 from the knife switch 7, through conductor 18, contactmember 24 of the circuit-breaker 12, conductor 25, contact member 47 ofthe circuit-breaker 12, conductor 48, contact terminal 49 of the mastercontroller 8. contact segments 62 and 63 which are electricallyconnected, contact terminal 52, conductor 53, actuating coil 46 of thecontactor 11, conductor 54, approximately one half of the startingresistor 10 and conductors 41 and 23 to the knife switch 7.

When the counter electromotive force of the motor 1 energizes theactuating coil 46 of the contactor 11 sufiiciently, the contactor11'will close, there-by shunting the starting res stor 10, as previouslyset forth.

If the master controller 8 is suddenly actuated from its forwardposition to its reverse position or vice versa, electrical braking orplugging of the motor 1 is effected. It is necessary to have thestartingresistor 10 in series with the motor and the contactor 11 opento prevent a heavy rush of current through the armature 4.

In a system arranged in accordance with my invention, the properprocedure is ensured, since the contactor 11 will not close until afterthe motor 1 has begun to actually operate in a reverse direction andbuild up its counter electromotive force. The

motor 1 would energ'ze the actuating coil 46 sufliciently to close thecontactor 11, if it were not balanced by the drop in potential acrossthat portion of the resistor 10 which is between the armature 4 of themotor 1 and the point where the conductor 54 is electrically connectedto the starting resistor 10.

Referring to Fig. 3, the motor 1 having shunt field-magnet winding 2,series fieldmagnet winding-3 and armature 4 is electrically energizedfrom the line conductors 5 and 6 through the knife switch 7. Theenergization of shunt field-magnet winding 2 is controlled by therheostat 9. The starting resistor 10 is-in series with the armature 4 ofthe motor 1.

The motor 1 is started directly from a master controller 7 0, whichcontrols the forward and the reverse operation of the motor 1. Ano-voltage release device 71 is connected in series relation with thearmature 4 of the motor 1 and prevents the operation of the motor 1 uponfailure ,of the line voltage. The contactor 11 isprovided for shuntingthe starting resistor 10 during the starting of the motor 1.

The operation of the control system is begun by closing the knife switch7. The ac- -'tuating coil 73 of the no-voltage release device 71 isenergized by a circuit that extends from the knife switch 7 throughconductors 74 and 75, contact terminal 76 of the controller 70, contactsegment 77, contact terminal 78, conductor 79, contact terminal 80,

conductor 81, series field-magnet winding 3 of the motor 1, conductor82, resistor 84, actuating coil 73 of the device 71, and conductor 86 tothe knife switch 7. When this circuit is completed, the device 71 isclosed by the actuating coil 73.

A holding circuit for the device 71 is provided from the knife switch7.through conductors 74 and 87 contact member 88 of the device 71,conductor 89, resistor 84, actuating coil 73 of the device 71 andconductor 86 to the knife switch 7. When the voltage through theactuating coil 73 falls below a predetermined value, the device 71 opensand the holding circuit is thereby broken. It

is possible to close the device 71 only by bringing the mastercontroller to the off position shown in the drawing.

The device 71 and the knife switch 7 being closed, the motor 1 may beoperated in a forward direction byactuating the master controller 70 toits forward position. A circuit is established thereby from the knifeswitch 7 through conductors 74 and 87, contact member 88 of the device71, conductors 89 and 82, series field-magnet winding 3 of the motor 1,conductor 81, contact terminal 80 of the controller 70, contact segment90, c n act terminal 91, conductor 92, the armature 4 of the motor 1,conductor 93, contact terminal 94 of the controller 7 0, contact segment95, contact terminal 96, conductor 97, the starting resistor 10 andconductor 99 to the knife switch 7.

The shunt field-magnet winding 2 of the motor 1 is energized as soon asthe device 71 isclosed by a circuit established from the knife switch 7,through conductors 74 and 87, contact member 88 of the contactor 71,conductors 89 and 82, shunt field-magnet winding 2 of the motor 1,conductor 101, field rheostat 9 and conductors 102 and 86 to the knifeswitch 7. The motor 1 is operated in a forward direction as soon as thearmature 4, the series field-magnet winding 3 and the shunt field-magnetwinding 2 are energized.

In addition, when the master controller 70 is moved to its forwardposition, a circuit for the actuating coil 103' of the contactor 11 isestablished from the knife switch 7 through conductors 74 and 87,contact member 88 of the contactor 71, conductors 89 and 82, seriesfield-magnet winding 3, conductor 81, contact termlnal 80, conductor 79,contact terminal 78 of the controller 70, contact segments 77 and 104,which are electrically connected, contact terminal 105, conductor 106,actuating coil 103 of the contactor 72, resistor 107, conductor 108,approximately half of the starting resistor 10 and conductor 99 to theknife switch 7.

When the counter electromotive force of the motor 1 is sufficient to soenergize the actuating coil 103 of the contactor 11 that it closes thecontactor 11, the starting resistor 10 is shunted to complete the motoracceleration.

By placing the resistor 107 in series with the actuating coil 103 of thecontactor 11, a relatively high counter electromotive force is requiredto energize the actuating coil 103 sufiiciently to close the contactor11, as previously explained.

Whenever the master controller 70 is moved to its reverse position, a.circuit is established from the knife switch 7 through conductors 74 and87 contact member 88 of the device 71, conductors 89 and 82, seriesfield-magnet winding'3, conductor 81, con tact terminal 80 of thecontroller 70, contact segments 112 and 113, which are electricallyconnected, contact terminal 94, conductor 93, armature 4 of the motor 1,conductor 92, contact terminal 91 of the controller 70, contact segments114 and 115, which are electrically connected, contact terminal 96,conductor 97. starting resistor 10 and conductor 99 to the knife switch7.

The motor 1 will now operate in a reverse direction, as the currentthrough the armature 4 thereof has been reversed, while the energizationof the series field-magnet winding 3 and the shunt field-magnet winding2 is in the same direction as for forward opere ation of the motor 1.

In addition, when the master controller 70 is actuated to its reverseposition, the actuating coil 103 of the contactor 11 is electricallyconnected in shuntrelation to the armature 1 and a portion of thestarting resistor 10, by a circuit established from the knife switch 7through conductors 74 and 87, contact member 88 of the device 71,conductors 89 and 82, series field-magnet winding 3 of the motor 1,conductor 81, contact terminal 80, conductor 79, contact terminal 78 ofthe controller 70, contact segments 77 and 116, which are electricallyconnected, contact terminal 105, conductor 106, actuating coil 103 ofthe contactor 11, resistor 107, conductor 108, approximately half of thestarting resistor 10 and conductor 99 to the knife switch 7. As soon asthe counter electromotive force of the motor 1 has sufficientlyenergized the actuating coil 103, the contactor 11 will close.

The contactor 11 will not close if the master controller is suddenlyreversed, to plug the motor, until the counter electromotive force hasbeen built up in the opposite direction. The drop in potential acrossthat portion of the starting resistor 10 which is between the armature 4and the point Where the conductor 108 is connected to the startingresistor counter-balances the generator effect of the armature 4 of themotor 1 to prevent sufficient energization of the actuating coil 103 toclose the contactor 11.

From the above description, it is apparent that I have provided meansfor closing a circuit-breaker in series with a motor and for maintainingit. closed, and that such means is protected from a heavy rush ofcurrent through the motor 1. I have also provided means forautomatically shunting the starting resistor of a motor which will onlyoperate after the motor has been brought to a predetermined speed ineither a forward or a reverse direction and protective means forpreventing the. shunting of the starting resistor when the motor is usedfor electrical braking.

While I have shown my invention in a preferred form, it is apparent thatminor modifications may be made in the apparatus and arrangement of thecontrol circuits without departing from the spirit thereof. I desiretherefore, to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a motor-control system, the combination with an electrical device,a switch for starting said device and means comprising an actuating coilfor closing said switch, means for energizing said coil, meanselectrically connected to said device for maintaining said coilenergized after the closing of said switch, and means for preventing thestarting of said device through said maintaining means.

2. In amotor-control system, the combination with an electrical device,a switch for starting said device, means comprising an actuating coilfor closing said switch,

means for energizing said coil, means comprising a holding circuit inshunt relation to said electrical device for maintaining said coilenergized, and meals for preventing the starting of said device throughsaid energizing. means and said maintaining means.

3. In a motor-control system, the combination with a motor, a contactorfor energizing said motor, and an actuating coil operatingsaidcontactor, of means for energizing said coil, means for maintainingsaid coil energized, and means for preventing the starting of said motorthrough said energizing means.

4. In a motor-control system, the combination with a motor, a contactorfor energizing said motor, and means comprising an actuating coil foroperating said contactor, of means for energizing said coil, a resistorin series with said means, and means independent of said resistor formaintainingsaid actuating coil energized after the closing of saidcontactor.

5. In a motor-control system, the combination with a motor, a contactorfor energizing said motor and means comprising an actuating coil foroperating said contactor, of means for energizing said coil, a resistorin series with said energizing means, and a holding circuit comprising asecond resistor for maintaining said actuating coil energizedindependently of said first resistor.

6. In a motor control system, the combination with a motor, of acontactor having an actuating coil for energizing said motor, aresistor, a switch associated with said resistor for energizing saidcoil and means comprising a second resistor for maintaining said coilenergized, said first and second resistor being connected in parallelrelation during the concurrent operation of Said switch and saidcontactor.

In testimony whereof, I have hereunto subscribed my name this 14th dayof September, 1920.

